Increased red blood cell alloimmunization rates in transfused aplastic anemia and myelofibrosis patients

BACKGROUND

Red blood cell (RBC) alloimmunization (AI) is a well-known complication of RBC transfusions, which results in the formation of alloantibodies to non-self antigens on donor RBCs, putting patients at risk of transfusion-related complications. The rate of AI with RBC transfusions in the general hospitalized population is estimated to be 2%-3%. However, some patients who are deemed "transfusion-dependent" require regular transfusions of blood products due to persistently low cell counts, putting them at even greater risk of RBC AI and increased morbidity. However, few studies currently exist investigating RBC AI in some transfusion-dependent patient populations, e.g., aplastic anemia (AA) and myelofibrosis (MF).

STUDY DESIGN AND METHODS

We conducted a 5-year retrospective review to investigate the prevalence of RBC AI, alloantibody incidence, and the number of RBC transfusions in AA and MF patients, who received RBC transfusions within our hospital system.

RESULTS

During the study period, 64 AA and 93 MF patients received 1301 and 2766 RBC transfusions, respectively. Compared to the RBC AI rate in the generalized hospitalized patient population (1%-2%), patients with AA and MF had an increased rate of RBC AI incidence rate at 14.1% and 12.9%, respectively. Furthermore, patients with primary MF demonstrated an isolated increased RBC AI incidence rate of 13.3%. The most common alloantibodies produced were anti-E and anti-K.

DISCUSSION

Within our institution, patients with AA and MF had increased incidence rates of RBC AI compared to the general hospitalized patient population and may benefit from an antigen-matched protocol to minimize AI-related complications.

Massive Transfusion Protocol Adherence: Relationship to Trauma Patient Outcomes

BACKGROUND

Ongoing evaluation of massive transfusion protocol adherence is critical to ensure better trauma patient outcomes.

OBJECTIVE

This quality improvement initiative aimed to determine provider adherence to a recently revised massive transfusion protocol and its relationship to clinical outcomes among trauma patients requiring massive transfusion.

METHODS

A retrospective, descriptive, correlational design was used to determine the association between provider adherence to a recently revised massive transfusion protocol and clinical outcomes in trauma patients with hemorrhage treated at a Level I trauma center from November 2018 to October 2020. Patient characteristics, provider massive transfusion protocol adherence, and patient outcomes were assessed. Patient characteristics and massive transfusion protocol adherence associations with 24-hr survival and survival to discharge were determined using bivariate statistical methods.

RESULTS

A total of 95 trauma patients with massive transfusion protocol activation were evaluated. Of the 95, 71 (75%) survived the initial 24 hr following massive transfusion protocol activation and 65 (68%) survived to discharge. Based on protocol applicable items, the median massive transfusion protocol overall adherence rate per patient was 75% (IQR = 57.1-85.7) for the 65 survivors and 25% (IQR = 12.5-50.0) for the 21 nonsurvivors to discharge whose death occurred at least 1 hr after massive transfusion protocol activation (p < .001).

CONCLUSION

Findings indicate the importance of ongoing evaluations of adherence to massive transfusion protocols in hospital trauma settings to target areas for improvement.

Hospital red blood cell and platelet supply and utilization from March to December of the first year of the COVID-19 pandemic: The BEST Collaborative Study

Background

At the start of the coronavirus disease 2019 (COVID‐19) pandemic, widespread blood shortages were anticipated. We sought to determine how hospital blood supply and blood utilization were affected by the first wave of COVID‐19.

Study Design and Methods

Weekly red blood cell (RBC) and platelet (PLT) inventory, transfusion, and outdate data were collected from 13 institutions in the United States, Brazil, Canada, and Denmark from March 1st to December 31st of 2020 and 2019. Data from the sites were aligned based on each site's local first peak of COVID‐19 cases, and data from 2020 (pandemic year) were compared with data from the corresponding period in 2019 (pre‐pandemic baseline).

Results

RBC inventories were 3% lower in 2020 than in 2019 (680 vs. 704, p < .001) and 5% fewer RBCs were transfused per week compared to 2019 (477 vs. 501, p < .001). However, during the first COVID‐19 peak, RBC and PLT inventories were higher than normal, as reflected by deviation from par, days on hand, and percent outdated. At this time, 16% fewer inpatient beds were occupied, and 43% fewer surgeries were performed compared to 2019 (p < .001). In contrast to 2019 when there was no correlation, there was, in 2020, significant negative correlations between RBC and PLT days on hand and both percentage occupancy of inpatient beds and percentage of surgeries performed.

Conclusion

During the COVID‐19 pandemic in 2020, RBC and PLT inventories remained adequate. During the first wave of cases, significant decreases in patient care activities were associated with excess RBC and PLT supplies and increased product outdating.

Massive Transfusion Protocol Predictive Modeling in the Modern Electronic Medical Record

Objectives

Integrate a predictive model for massive transfusion protocol (MTP) activation and delivery in the electronic medical record (EMR) using prospectively gathered data; externally validate the model and assess the accuracy and precision of the model over time.

Background

The Emory model for predicting MTP using only four input variables was chosen to be integrated into our hospital's EMR to provide a real time clinical decision support tool. The continuous variable output allows for periodic re-calibration of the model to optimize sensitivity and specificity.

Methods

Prospectively collected data from level 1 and 2 trauma activations were used to input heart rate, systolic blood pressure, base excess (BE) and mechanism of injury into the EMR-integrated model for predicting MTP activation and delivery. MTP delivery was defined as: 6 units of packed red blood cells/6 hours (MTP1) or 10 units in 24 hours (MTP2). The probability of MTP was reported in the EMR. ROC and PR curves were constructed at 6, 12, and 20 months to assess the adequacy of the model.

Results

Data from 1162 patients were included. Areas under ROC for MTP activation, MTP1 and MTP2 delivery at 6, 12, and 20 months were 0.800, 0.821, and 0.831; 0.796, 0.861, and 0.879; and 0.809, 0.875, and 0.905 (all P < 0.001). The areas under the PR curves also improved, reaching values at 20 months of 0.371, 0.339, and 0.355 for MTP activation, MTP1 delivery, and MTP2 delivery.

Conclusions

A predictive model for MTP activation and delivery was integrated into our EMR using prospectively collected data to externally validate the model. The model's performance improved over time. The ability to choose the cut-points of the ROC and PR curves due to the continuous variable output of probability of MTP allows one to optimize sensitivity or specificity.

Comparison of the platelet activation status of single-donor platelets obtained with two different cell separator technologies

BACKGROUND

The microparticle content (MP%) of apheresis platelets-a marker of platelet activation-is influenced by donor factors and by external stressors during collection and storage. This study assessed the impact of apheresis technology and other factors on the activation status (MP%) of single-donor apheresis platelets.

STUDY DESIGN AND METHODS

Data from six US hospitals that screened platelets by measuring MP% through dynamic light scattering (ThromboLUX) were retrospectively analyzed. Relative risks (RRs) were derived from univariate and multivariable regression models, with activation rate (MP% ≥15% for plasma-stored platelets; ≥10% for platelet additive solution [PAS]-stored platelets) and MP% as outcomes. Apheresis platform (Trima Accel vs Amicus), storage medium (plasma vs PAS), pathogen reduction, storage time, and testing location were used as predictors.

RESULTS

Data were obtained from 7511 platelet units collected using Trima (from 16 suppliers, all stored in plasma, 20.0% were pathogen-reduced) and 2456 collected using Amicus (from four different collection facilities of one supplier, 65.0% plasma-stored, 35.0% PAS-stored, none pathogen-reduced). Overall, 30.0% of Trima platelets were activated compared to 45.6% of Amicus platelets (P < .0001). Multivariable analysis identified apheresis platform as significantly associated with platelet activation, with a lower activation rate for Trima than Amicus (RR: 0.641, 95% confidence interval [CI]: 0.578; 0.711, P < .0001) and a 6.901% (95% CI: 5.926; 7.876, P < .0001) absolute reduction in MP%, when adjusting for the other variables.

CONCLUSION

Trima-collected platelets were significantly less likely to be activated than Amicus-collected platelets, irrespective of the storage medium, the use of pathogen reduction, storage time, and testing site.

Effects of repleting organic phosphates in banked erythrocytes on plasma metabolites and vasoactive mediators after red cell exchange transfusion in sickle cell disease

BACKGROUND

Red blood cell (RBC) exchange (RCE) transfusion therapy is indicated for certain patients with sickle cell disease (SCD). Although beneficial, this therapy is costly and inconvenient to patients, who may require it monthly or more often. Identification of blood and plasma biomarkers that could improve or help individualise RCE therapy is of interest. Here we examined relevant blood and plasma metabolites and biomarkers of vasoactivity and RBC fragility in a pilot study of SCD patients undergoing RCE using either standard RBC units or RBC units treated with a US Food and Drug Administration (FDA)-approved additive solution containing phosphate, inosine, pyruvate, and adenine ("PIPA").

MATERIALS AND METHODS

In this prospective, single-blind, cross-over pilot clinical trial, patients were randomised to receive either standard RBC exchange or PIPA-treated RBC exchange transfusion with each RCE session over a 6-month treatment period. Pre- and post-transfusion blood samples were obtained and analysed for RBC O₂ affinity, ATP, purine metabolites, RBC microparticles, and cell free haemoglobin.

RESULTS

Red blood cell O₂ affinity was maintained after PIPA-RCE in contrast to standard RCE, after which P₅₀ fell (net O₂ affinity rose). Plasma ATP did not change significantly after RCE using either of the RBC unit types. Exchange transfusion with PIPA-treated RBC units led to modest increases in plasma inosine and hypoxanthine. Plasma cell free haemoglobin fell after either standard or PIPA-treated RBC exchange transfusion (novel findings), and to a similar extent. RBC-derived microparticles in the plasma fell significantly and similarly after both standard and PIPA-treated RCE transfusion.

DISCUSSION

In summary, treatment of RBCs with PIPA prior to RCE elicited favourable or neutral changes in key metabolic and vascular biomarkers. Further study of its efficacy and safety is recommended and could ultimately serve to improve outcomes in chronically transfused SCD patients.

Rejuvenation solution as an adjunct cold storage solution maintains physiological haemoglobin oxygen affinity during early-storage period of red blood cells

BACKGROUND

Red blood cell (RBC) units accumulate morphologic and metabolic lesions during storage before transfusion. Pyruvate-inosine-phosphate-adenine (PIPA) solutions (Rejuvesol, Biomet, Warsaw, IN) can be incubated with RBC units to mitigate storage lesions. This study proposes a PIPA treatment process, termed cold 'rejuvenation', using Rejuvesol as an adjunct additive solution, to prevent biomechanical storage lesions while avoiding the 1 h PIPA incubation required with standard PIPA treatment. We compared the efficacy of cold to standard 'rejuvenation' in improving metabolic lesions that occur during cold storage of RBCs, without altering function.

METHODS

Twelve leucoreduced, A-positive RBC units were obtained. Each unit was aliquoted into either control (standard storage), washed (W), standard rejuvenation (SR) or cold rejuvenation (CR) groups, the latter two requiring washing. A volume-adjusted dose of Rejuvesol was instilled into the CR group upon receipt (Day 3). After 15 days of storage, p50, RBC deformability, in-bag haemolysis and mechanical fragility were analysed. 'Any treatment' is defined as W, SR and CR, with comparisons in reference to control.

RESULTS

Higher p50s were seen in rejuvenated groups (>30 mmHg vs. <19 mmHg; P < 0·0001). Any treatment significantly increased elongation index (P = 0·034) but did not significantly increase in-bag haemolysis (P = 0·062). Mechanical fragility was not significantly different between groups (P = 0·055) at baseline, but the control (CTL) group was more fragile after 2 h in a cardiac bypass simulation than any treatment (P < 0·0001).

CONCLUSIONS

This study demonstrates that rejuvenation (standard or cold) prevents the leftward p50 shift of storage lesions without detrimental effect on RBC deformity, in-bag haemolysis or mechanical fragility.

Estimation of Achievable Oxygen Consumption Following Transfusion With Rejuvenated Red Blood Cells

Erythrocyte storage induces a nonphysiological increase in hemoglobin-oxygen affinity (quantified by low p50, the oxygen tension at 50% hemoglobin saturation), which can be restored through biochemical rejuvenation. The objective was to mathematically model the impact of transfusing up to 3 standard allogeneic units or rejuvenated units on oxygen delivery (DO₂) and oxygen consumption (VO₂). Oxygen dissociation curves were generated from additive solution-1 red blood cell (RBC) leukoreduced units (n = 7) before and after rejuvenation following manufacturer's instructions. Two of these units were used to prepare standard or rejuvenated donor RBC and added to samples of fresh whole blood. These admixtures were used to construct an in vitro transfusion model of postoperative anemia and determine a linear equation for calculating the sample p50, which was subsequently used to calculate DO₂ and VO₂ after simulated transfusions. Whole blood-packed red blood cell unit admixture p50s could be predicted from a linear model including the p50 of its components, the mass fraction of the transfused component, and interaction terms (R² = .99, P < 0.001). Transfusion with standard units slightly, but significantly, increased projected DO₂ compared with rejuvenated units (P = 0.03), but rejuvenated units markedly increased projected VO₂ (P = 0.03). Standard units did not significantly change VO₂ relative to pre-transfusion levels (P > 0.1). Using high-p50, rejuvenated RBC in simulated transfusions greatly improved projected VO₂, indicating the potential for increased end-organ oxygen availability compared with standard transfusion. Patient capacity to increase cardiac output after cardiac surgery may be limited. Transfusing high-p50 RBC in this setting may improve the perioperative care of these patients.

Inventory management strategies that reduce the age of red blood cell components at the time of transfusion

BACKGROUND

There has been interest concerning patient outcomes when older red blood cell (RBC) components are utilized. Inventory management is key to maintaining a stock of fresher RBCs for general transfusion needs. We have altered our practice for RBC management to reduce RBC age at the time of transfusion.

STUDY DESIGN AND METHODS

Retrospective review of RBC age at time of transfusion at a tertiary care hospital with active trauma service was performed. The baseline nonirradiated RBC inventory was decreased from 12 to 15 days of stock to 7 to 10 days of stock, with request made to the blood supplier for fresher RBCs, specified at 75% of RBCs less than 14 days old. The age of RBCs at time of receipt and at time of transfusion was tracked on a monthly basis for the next 12 months.

RESULTS

The mean age of RBCs at transfusion was decreased by 9 days on average for the year. Significant decreases in the mean age of RBCs at transfusion were seen in the second half of the year, with 4 of 6 months seeing a mean age of less than 20 days. There were no documented incidences of hospital blood shortages after the reduction in inventory; no surgery was canceled or delayed because of inventory.

CONCLUSION

Inventory age depends on active management, combined with vendor cooperation to receive fresher components. Reducing the age of RBC components transfused is possible without experiencing blood component shortages. Longer periods of observation may allow for further adjustment of stocking levels on a seasonal basis.

Non-specific red cell reactivity in an obstetric population

OBJECTIVE

To examine non-specific red cell reactivity (NSR) on antibody (Ab) screening of obstetric inpatients.

METHODS

Observational study of 5438 obstetric inpatients (2009-2013). Ab-positive patients were identified and their records reviewed for NSR, other antibodies, transfusion reactions or hemolytic disease of the fetus/newborn (HDFN). Evaluation of NSR frequency by test era assessed the impact of an institutional change to solid-phase screening in 2011.

RESULTS

Of obstetric inpatients, 5.3% had at least one positive Ab screen; 1.6% had NSR. Of NSR-positive patients, 16.7% had identifiable Abs that pre-dated NSR; 25% had concurrent Abs and 8.5% had subsequent Ab identification. In 49.1%, NSR resolved during follow-up. The frequency of NSR was higher after the change to solid-phase Ab screening, but specific Ab frequency was similar in both testing periods. No transfusion reactions or cases of HDFN were noted in this cohort.

CONCLUSIONS

NSR is found in 1-2% of obstetrical inpatients at our institution, and has more than doubled since the initiation of solid-phase screening. Although likely clinically insignificant by itself, NSR is commonly found in relation to other red cell Abs and may precede their development.

Rapid increases in parasitemia following red cell exchange for malaria

Exchange transfusion is frequently used as an adjunctive treatment of severe malaria, although the efficacy of exchange transfusion as therapy for severe malaria remains controversial. The major perceived benefit of exchange transfusion is the rapid reduction of parasite load. However, no previous report has shown the dynamic change in parasitemia shortly following an acute load reduction. We report a 20-year-female who developed cerebral malaria and 30% parasitemia after traveling to Africa. In addition to antimalarial treatment, red cell exchange (RCX) was begun emergently with an automated blood-cell separator. Parasitemia dropped from 30 to 15% immediately after the procedure but rapidly increased to 25% after 50 min. The second procedure was performed 12 h after the first procedure. Her neurologic status returned to baseline on Day 2, and she was discharged on Day 6. Rapid increases in parasitemia can be observed after mechanical load reduction following RCX.